Will do, these are just latest developments. It will work with 0.33R and 0.12R resistors, but just burn a lot of heat. The feedback resistor value of 22k is still recommended by Hugh if you don't have a preamp with gain. So I would leave that as is for now. I might just add a note in red text next to the schematic on the first post (only post that can be editied in time).
Nice work JP! Beautiful look with a bizzilion vias! The PCB board fab houses will love this design. Can’t inagine how many drill bits they will go through?
It reminds me of filigree in archaic artwork with detailing. Do the plated vias dexrease Wright or increase weight of boards?
I like the breakout PWM fan controller boards too! Nice touch.
It reminds me of filigree in archaic artwork with detailing. Do the plated vias dexrease Wright or increase weight of boards?
I like the breakout PWM fan controller boards too! Nice touch.
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I did an experiment last night and reduced R113 to 15k for a 23.5dB gain amp. This in combination with the Aksa Lender Preamp running with 6k8 feedback resistors in combination produced an unbelievably good sound. I was listening to a 1956-1957 recording of Ella Fitzgerald and Louis Armstrong, a CD I have had for many years, but now it is like WOW, the vocals clarity, dynamics, depth of realism, it was like they were there in my lab - singing live. The nuances and emotions of “Summertime” was something was not quite prepared to experience. Just wonderful - I almost slipped into staying up all night just to listen over my music collection but had some self control and stopped at 330AMWork today still has to get done despite my wishes to just enjoy my music.
This works because I am driving with a good preamp. If you don’t have a preamp, you should probably keep it at usual 27dB gain with R113 set at 22k.
I have asked Vunce to try same configuration to see if he experiences similar increase in SQ. So with experience we are seeing some fine points of the setup that might be customized depending on your application.
So the ALPHA is back on the bench for another tweak. I removed the 22K carbon resistors and installed pin sockets to make resistor swapping quick and easy. My AKSA Lender preamp is set up for a gain of approximately 15dB. I installed 15K Takman’s in the ALPHA and had a listen. Wow! My Forte’s disappeared, the soundstage is the entire wall. Also, the reduced gain enables finer volume adjustment per step. Since this worked well, I went a step further and installed 12K PRP metal film resistors. This combo works excellent for my setup, they will stay..... for now
GB2 Status....
Please add name to interest list, once we reach 10 pairs, I can arrange for invoices to be sent and production to commence. I found out the hard way that the GB takes a lot of time so I will have to increase the price a bit to $28/pair. Shipping is still $5 in US, $10 to Canada, and $15 for everywhere else.
Interest List:
Please add name to interest list, once we reach 10 pairs, I can arrange for invoices to be sent and production to commence. I found out the hard way that the GB takes a lot of time so I will have to increase the price a bit to $28/pair. Shipping is still $5 in US, $10 to Canada, and $15 for everywhere else.
Interest List:
Yes, no problem. Match the Hfe on the A992 though for thermal tracking. This amp is absolutely zero adjustments. I haven’t touched any pot at all and 0mV DC offset (from cold to hot) on all amps built. Bias is rock steady and set by R131.
Those are all options (different hole spacings) for whatever you feel is best for input caps. Some people don’t believe in bypass caps. A $0.35 10uF 35V Silmic II is an excellent choice all by itself. Or some like 1uF film added as bypass. I am using 6.8uF 250V film cap all by itself but I think even 4.7uF could work. For deepest bass extension a 10uF is suggested. Plenty of 10uF 400v MKP axial caps that fit here. Some may opt for silver foil in oil boutique caps, or gold foil in wax, etc. Have fun cap rolling!
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Maybe I just leave that Silmic in place and that's it for now
just ordered new R131 and R132 resistors (Philips 0,47ohm and 0,22ohm, can't get metal oxides locally it seems). What needed if I steal some power from rectifiers to fans?